The primary factors influencing the design of collapsible, portable building systems are the ease of assembly and disassembly, ease of transport in their collapsed condition and the overall comfort and/or practicality of the shelter for its intended use once it has been erected. There is among presently available designs considerable room for improvement in each of the above characteristics, particularly as they relate to the use of such systems in remote locations under extreme climatic conditions such as high winds, severe temperatures and blowing sand and snow. Known portable and collapsible building systems vary in design from simple tents to complex folding buildings. Typically, one or more of the following problems exists with each of the known designs. The structures may require heavy equipment such as cranes or winches to erect. They may be awkward to transport to remote off-road regions, that is they may be heavy, bulky or of a shape which is not adaptable to a wide variety of transport means. They may be complex and thus time consuming to erect by involving a great number of loose parts in the construction and erection and thereby increasing the chances of equipment failure or the loss of small pieces or items of essential hardware. Another problem is that the structure may simply be ineffective in a hostile environment. Finally, some designs may not be expandable into variable sized buildings which are adaptable to a wide variety of uses.
Among the patented prior art devices of which applicants are aware are the following U.S. Pat.: Nos. 4,534,141; 4,133,149; 4,085,762; 3,971,395; 3,763,607; 3,629,982; 3,421,268; 3,338,003; 3,284,966; 3,103,709; 2,904,850; 2,797,696; 2,765,499; 2,751,635; 2,693,195; 2,632,454; 2,363,917; and 2,363,916. None of the cited prior patents is pertinent in terms of its structure or construction principles to the invention herein other than for isolated features.